1. Field of the Invention
The present invention relates to a recording mode discriminating apparatus for discriminating the recording mode of a recording medium such as a recording tape in the fast feeding or rewinding reproduction mode corresponding to a tape type recording medium recording/reproducing apparatus such as a VTR (Video Tape Recorder) which performs tracking control, for example, by the ATF (Automatic Track Finding)system and more particularly to a recording mode discriminating apparatus to be provided in a VTR comprising a liquid crystal display apparatus as a monitor apparatus.
2. Description of the Related Art
As a VTR, for example, particularly in so-called a portable type camcorder, etc., those providing a liquid crystal display apparatus for monitoring a reproduced image or a pickup image are widely spreading.
A VTR comprising a liquid crystal display apparatus as explained above is assumed to introduce a system for recording to the tracks on the guardbandless basis through the helical scanning with a pair of heads in different azimuth angles, for example, which are provided in the opposition angle of 180.degree. for a rotating drum. It is known that when an image of fast feeding or rewinding reproduction is attempted to be displayed in direct on such a liquid crystal display apparatus, noise bars are appearing in the horizontal direction in the fast feeding/rewinding reproduction image corresponding to the period where the reproduced RF signal becomes insufficient because the head is crossing a plurality of tracks.
Therefore, as disclosed, for example, in the Japanese Patent Application Laid-Open No. HEI 2-137586, the inventors of the present invention have proposed previously a structure whereby noise bars explained above are not appearing in the image of the liquid crystal display apparatus during the fast feeding/rewinding reproduction mode.
In this invention, a liquid crystal display apparatus which is driven by the matrix system is assumed to be provided. In the fast feeding/rewinding reproduction mode, a magnetic tape is caused to run at the speed equal to the predetermined even number times the speed of the ordinary reproducing mode. When the tape is run at the even number times speed, it is known that the period in which the reproduced RF signal becomes insufficient, namely the position where noise bar appears as a reproduced image differs in the horizontal direction in each field.
Therefore, during the ordinary fast feeding/rewinding reproduction mode at the speed equal to the even number times the ordinary tape running speed, the fast feeding/rewinding reproduction mode image in which the noise bars are eliminated can be displayed by stopping the supply of a horizontal scanning signal to drive the liquid crystal display apparatus in the period corresponding to the part where the reproduced RF signal is insufficient, namely the reproduced image can be considered unnecessary in order to display the image portion of the just preceding field (an image of this part is displayed based on the reproduced RF signal of the sufficient level) by making use of the holding effect of the liquid crystal display apparatus.
In a 8 mm VTR, for example, as the VTR having introduced the ATF tracking control system without using the control track, the so-called "4-frequency ATF system" utilizing four kinds of pilot signals of predetermined different frequencies has been employed. In this 4-frequency ATF system, such four kinds of pilot signals are sequentially recorded in the track by the rotational manner. During the reproduction mode, the tracking control is performed so that the reproducing head adequately traces the target track depending on the tracking error signal which is generated on the basis of the reference pilot signals (in the same frequencies as the four kinds of pilot signals explained above) which is sequentially rotated corresponding to the pilot signal (reproduced pilot signal) obtained from the reproduced RF signal and the scanning timing of head (for example, field timing).
Moreover, a known 8 mm VTR which has employed the 4-frequency ATF system as explained above is provided, as the recording mode, with the standard mode (SP ode) which realizes recording to the track by causing a magnetic tape to run at the standard speed and a long playing mode (LP mode) which realizes, as a result, the recording time corresponding to almost two times that in the SP mode for the magnetic tape of the same length by executing the recording to the track, for example, in the tape running speed of a half time (1/2 time) the standard speed as explained above.
Therefore, it is naturally thought that the region where recording has been performed in the SP mode and the region where recording has been performed in the LP mode exist, for example, in the mixed manner on the same magnetic tape. For example, when the region on the magnetic tape changes to the region recorded by the LP mode from the region recorded by the SP mode depending on the running of the tape even in the fast feeding/rewinding reproduction mode as the special reproduction mode as well as in the ordinary reproduction mode, the reproducing operation condition corresponding to the SP mode must be changed to the condition corresponding to the LP mode in order to adequately display the fast feeding/rewinding reproduction mode image of the region recorded by the LP mode. In the same manner, when the region on the magnetic tape changes to the region recorded by the SP mode from the region recorded by the LP mode during the fast feeding/rewinding reproduction mode, the reproducing operation condition corresponding to the LP mode must be changed to the condition corresponding to the SP mode.
In order to realize the switching of the tape running speed in the fast feeding/rewinding reproduction mode depending on the recording mode as explained previously, it is essential in the fast feeding/rewinding reproduction mode to discriminate by which mode of the SP mode and LP mode the track of the magnetic tape during the reproduction mode is recorded and a structure for discriminating such recording mode has been proposed in the Japanese Patent Application LaidOpen No. SHO 62-184646 by the inventors of the present invention.
In this invention, the tape running speed during the fast feeding/rewinding reproduction mode is set to the predetermined odd number times the ordinary reproduction speed and then the tracking error signal obtained as explained above is sampled with the predetermined timing. In this case, a sampling output has an intrinsic time series pattern which is different for each relationship between the recording mode of the magnetic tape and tape running speed and therefore the recording mode of the magnetic tape can be discriminated by making reference to the time series pattern of the sampling output.
With the background described above, for example, in a 8 mm VTR (camcorder) comprising a current liquid crystal display apparatus, noise bars do not appear in the liquid crystal display screen by setting the tape running speed in the fast feeding/rewinding reproduction mode to odd number times the ordinary reproduction speed under the condition that the liquid crystal display mode is set to OFF state and display of the reproduced image by the liquid crystal display apparatus is not required or by setting the tape running speed to even number times the ordinary reproduction speed under the condition that the liquid crystal display mode is set to ON state.
However, when the recording mode discrimination of the magnetic tape is attempted during the fast feeding/rewinding reproduction in the 8 mm VTR introducing the structure explained above, since the tape running speed is set to the odd number times the ordinary reproduction speed under the condition that the liquid crystal display mode is in the OFF state, the recording mode can be discriminated without any problem by monitoring, conforming to the structure disclosed in the Japanese Patent Application Laid-Open No SHO 62-184646 described previously, a time series change of sample output of the tracking error signal which is obtained depending on the reproduced pilot signal and the reference pilot signal which is rotated in the field timing.
On the other hand, it is known that, under the condition that the liquid crystal display mode is in the ON state, the tape running speed in the fast feeding/rewinding reproduction mode is set to the even number times the ordinary reproduction speed, but under the condition of the even number times speed, intrinsic time series pattern of the sample output of the tracking error signal does not appear in the SP mode and LP mode. Namely, there is a problem under this condition that discrimination of the SP/LP mode by the recording mode discrimination method explained above is very difficult.